In the atmosphere control industry, there are many occasions where mixtures of gases and liquids in a vapor form are necessary for various chemical processes. However, there have been problems in providing control of the vapor pressure of the liquid or liquids within the gas or gases. When handling small volumes of liquids, surface tension becomes an important factor. Spraying the liquid into an unsaturated gas becomes difficult from the spray nozzle design and the uniformity of the vapor pressure of the liquid obtained throughout the gas. Thermally vaporizing the liquid or liquids can cause problems because of thermal degradation to the liquids, safety considerations and the general expense of control.
Heretofore, a partial vapor pressure was provided by bubbling a partial stream of the carrier gas through the liquid and then combining the partial stream with the main stream of the carrier gas. This is referred to as sparging. This process did not provide proper control of the amount of liquids, for example water, added to the gas since the amount of water added using this process may change depending on ambient temperature, pressure control and water level control. See Glass To Metal Sealing: Improved Yields And Quality Using Nitrogen Based Atmospheres by Jerome J. Schmidt and Jerry Carter, International Microelectronics Symposium (ISHM 84) which uses an atmosphere flow control system including bubbling nitrogen through distilled water; U.S. Pat. No. 4,888,037 issued Dec. 19, 1989, which discloses a process for sealing glass to metal using a humidification method of bubbling gas through water; and Improved Glass To Metal Sealing Through Furnace Atmosphere Composition Control by Walter F. Yext and Bruce J. Shook of Air Products, and Wayne S. Katzenberger and Robert Michaleh from Elecpac Division of Wilbrecht Electronics, Inc., presented at the 33rd Electronics Components Conference in Orlando, Fla., May 1983, which deals with improved processes for more precise control over furnace atmosphere composition and which provides humidity in a nitrogen gas flow by bubbling the gas through a water vaporizer. This prior art approach to providing partial vapor pressure in gas streams has been extremely difficult to control and has caused many problems.